Approximately one billion people residing in major urban areas, as well as renowned monuments like the Empire State Building, have been invited to switch off the lights for Earth Hour. The event is led by the World Wildlife Federation, and has been described as the “biggest mass campaign to demand action on climate change,” according to Agence France-Presse.

The Great Pyramids of Giza, the Acropolis in Athens, and the Louvre in Paris are among the world-famous attractions participating in the hour of darkness, which begins at 8:30 p.m. local time, reported AFP.

Prominent officials and celebrities alike have been advocating for Earth Hour, including United Nations Secretary-General Ban Ki-moon, who “urged people to participate as a way of letting politicians know that they expect progress” at the Global Climate Change Conference next December, according to National Geographic News. Celebrities in favor of Earth Hour include actress Cate Blanchett and British band Coldplay.

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According to Stuff, New Zealand will be the first country to shut off the lights. The Chatham Islands will be the first to go dark, followed by 44 cities, regions and towns across the North and South Islands, as well as several “iconic buildings and places, including the Sky Tower, the Beehive and the Octagon in Dunedin.”

Small towns in the United States are getting in on the act, but taking safety into consideration. In Lower Pottsgrove Township, Pa., board members have agreed to “turn off as many lights as possible in the township municipal building" on Friday afternoon, rather than Saturday night. The board worried that Earth Hour could pose “hazards to citizens and drivers,” but wanted to participate.

According to The Sanatoga Post, the afternoon lights out event “may be only a symbolic gesture … but at least it united the township in spirit with the concept and limited risks to people.”

The official Earth Hour Web site invites participants to submit photos to the event's Flickr group, record a video of your Earth Hour experience and post it to YouTube, and share your thoughts on Earth Hour in a live blog post or on Twitter.

In March, a Bloomington, Minn., office building took steps to save birds' lives by turning off all lights between midnight and dawn. The bodies of dead songbirds had been appearing more frequently around the building after being drawn to and disoriented by the commercial lighting, which prompted the decision. Boston has undertaken a similar, but larger-scale, two-month initiative to conserve electricity by shutting off lights at 34 city skyscrapers between the Back Bay and South Boston waterfront.

In January, some areas of Britain turned off highway lighting in an effort to reduce energy costs and cut down on carbon emissions. The switch was also expected to “reduce light pollution of the night sky,” reported The Daily Telegraph, but police and scientists warned that turning off the lights would impact the safety of the area.